Vinyl aromatic aminimides and polymers thereof

ABSTRACT

WHEREIN R IS A HYDROGEN, METHYL, OR HALOGEN; N IS ZERO OR ONE AND R1, R2, AND R3 ARE HYDROCARBON RADICALS AND R1 AND R2 CAN BE COMBINED TO FORM A HETEROCYLIC RING WITH THE NITROGEN.   CH2=C(-R)-C6H4-(CH2)N-CO-N(-)-N(+)(-R1)(-R2)-R3   VINYL AROMATIC AMINIMIDES ARE PREPARED FROM VINYL AROMATIC ACIDS OR DERIVATIVES THEREOF. THE VINYL AROMATIC AMINIMIDE CAN BE HOMOPOLYMERIZED AND COPOLYMERIZED TO RESULT IN FUNCTIONAL GROUP-CONTAINING POLYMERIC PRODUCTS CAPABLE OF THERMOSETTING. THE VINYL AROMATIC AMINIMIDES HAVE THE GENERAL FORMULA

United States Patent O" US. Cl. 260--82.1 9 Claims ABSTRACT OF THEDISCLOSURE Vinyl aromatic aminimides are prepared from vinyl aromaticacids or derivatives thereof. The vinyl aromatic aminimide can behomopolymerized and copolymerized to result in functionalgroup-containing polymeric products capable of thermosetting. The vinylaromatic aminimides have the general formula wherein R is a hydrogen,methyl, or halogen; n is zero or one and R R and R are hydrocarbonradicals and R and R can be combined to form a heterocyclic ring withthe nitrogen.

This is a division of application Ser. No. 662,571 filed Aug. 23, 1967and now US. Pat. 3,641,145, issued Feb. 8, 1972.

The present invention relates to novel vinyl aromatic aminimides and topolymers thereof. In another aspect, the present invention relates toprocesses for the preparation of the vinyl aromatic aminimides, theirpolymerization, and the subsequent chemical modification of suchpolymers.

The vinyl aromatic aminimides of the present invention have the generalformula wherein R is a hydrogen, methyl, or halogen; n is zero or one; Rand R are aliphatic or aryl hydrocarbon radicals having from 1 to 22carbon atoms or radicals in which R and R are combined to formheterocyclic rings with the nitrogen; and wherein R is a saturated orunsaturated aliphatic hydrocarbon radical of 1 to 22 carbon atoms. Theterm aryl as employed herein is meant to define an aromatic radical inwhich the unsatisfied valence is at a carbon atom of the aromaticnucleus.

The aminimides of the present invention are prepared by reacting ahydrazine with a vinyl aromatic acid chloride in the presence of aninert organic solvent, subsequently reacting the hydrazine with aquaternizing agent to form the quaternary ammonium salt, and then dehy-Patented Sept. 4, 1973 drohalogenating the reaction product in thepresence of a base in accordance with the following reaction scheme inwhich R, R R and R and n have the above-indicated meaning, and X can beany suitable anion.

The unsymmetrical hydrazine employed in the formation of the aminimidesof the present invention can be obtained by the reaction of a halo-aminewith a tertiary amine, resulting in the hydrazinium salt which isreacted with a base to form the hydrazine. Since the reaction iswell-known in the art, no further description is deemed necessary.

The unsymmertical hydrazine is reacted with the vinyl aromatic acidchloride in the presence of an inert solvent such as a low boilinghydrocarbon solvent, commercially available as Skelly F, dimethyls-ulfoxide, acetonitrile, dioxane, tetrahydrofuran, ethers, e.'g.diethyl ether, glymes (i.e., dimethyl ethers of ethylene glycol), andthe like. The solvent is employed in sufiicient amounts to allow theformation of a fluid mixture. Preferably, the reaction is conducted atambient temperature and pressure conditions, although higher and lowertemperatures or higher and lower pressures can be employed if called forby the reagents employed in the particular synthesis. In general, thereaction conditions employed should provide for the removal of theby-prodnct HCl. Although the reaction proceeds rapidly, it is generallypreferred to employ longer reaction times to assure completion of thereaction and thereby higher yields of the vinyl aromatic hydrazine. Anexcess of either reagent may be employed, although such is not necessaryin view of the quantitative yields obtained by the use of nearlyequivalent amounts of the acid chloride and the hydrazine. The vinylaromatic hydrazine may precipitate out of the solvent, depending on thesolvent. If the vinyl aromatic hydrazine does not precipitate, it can bereadily isolated by evaporation of the solvent.

The vinyl aromatic hydrazine is quaternized with a compound having thegeneral formula wherein R is a saturated or unsaturated aliphatichydrocarbon radical and preferably a lower alkyl radical, and X can beany quaternizing anion but is preferably an aryl sulfonate radical or ahalogen radical such as chlorine, bromine or iodine.

Suitable quaternizing agents, therefore, include methyl chloride, methylbromide, ethyl chloride, methyl iodide, propyl chloride, ethyl bromide,methyl benzene sulfonate, methyl toluene sulfonate (methyl tosylate),and ethyl toluene sulfonate.

The reaction of the vinyl aromatic hydrazine with the quaternizing agentis preferably conducted in the presence of a solvent which is generallyof the type of inert solvent hereinabove indicated. Reactiontemperatures will vary from room temperature to elevated temperatureswhich do not cause the decomposition of the reagents or products.

The hydrazinium salt is dissolved in an alcohol such as methanol, anddehydrohalogenated to the aminimide by titrating with an alcoholic baseto a neutral end point. Preferred bases are the alkali metal bases suchas sodium hydroxide or potassium hydroxide. The aminimide is isolated byprecipitating the alkali metal salt and evaporating the solvent.

The unsymmetrical hydrazine, which is reacted with the vinyl aromaticacid chloride to form the vinyl aromatic hydrazine, has the generalformula wherein R and R have the above-indicated meaning.

Preferably, R and R are lower alkyl groups, phenyl and substitutedphenyl groups, and such heterocyclic ring compounds as pyrrolidine,pyrrole, pyrroline, and piperidine. Specific examples of theunsymmetrical hydrazines employed include dimethylhydrazine,diethylhydrazine, methyl-ethylhydrazine, dibutylhydrazine, N amino-2-phenyl pyrrolidine, phenyl-methylhydrazine, diphenylhydrazine, anddicresylhydrazine.

The vinyl group of the aromatic acid chloride can contain substituentson the a-carbon normally found in polymerizable substituted styrenessuch as methyl or halogen and particularly chlorine. The acyl halidegroup can be directly bonded to the benzene nucleus or can be bonded tothe benzene nucleus by means of a methylene group. The vinyl groupfurther can be ortho, meta, or para to the acyl halide group. Thus,suitable vinyl aromatic acid chlorides include 4-vinylbenzoyl chloride,3-vinylbenzoyl chloride, 2-vinylbenzoyl chloride,2-(ozmethylvinyl)benzoyl chloride, 3-(a-methylvinyl)benzoyl chloride,4-(a-methylvinyl)benzoyl chloride, Z-(a-ChlOIO- vinyl)benzoyl chloride,3-(a-chlorovinyl)benzoyl chloride, 4-(a-chlorovinyl)benzoyl chloride,(Z-vinylphenyl) acetyl chloride, (3-vinylphenyl)acetyl chloride,(4-vinylphenyl)acetyl chloride, 4 (a methylvinyl)phenylacetyl chloride,3-(a-methylvinyl)phenylacetyl chloride, and2-(a-methylvinyl)phenylacetyl chloride.

Aminimides which can be prepared by the described process includetrimethylamine-4-vinyl-benzimide, trimethylamine-3-vinyl-benzimide,trimethylamine-Z-vinyl-benzimide, dimethylethylamine-4-vinyl-benzimide,triethylamine-4-vinyl-benzimide,

dipropylmethylamine-4-vinyl-benzimide, tributylamine-4-vinylbenzimide,triethylamine-3-vinyl-benzimide, diethylmethylamine-Z-vinyl-benzimide,trimethylamine-4- 2-propeny1) benzimide,trimethylamine-3-(2-propenyl)benzimide,trimethylamine-2-(2-propenyl)benzimide,triethylamine-4-(2-propenyl)benzimide,trimethylamine-4-vinylphenyl-acetimide,trimethylamine-3-vinylphenyl-acetimide,trimethylamine-Z-vinylphenyl-acetimide,triethylamine-4-vinylphenyl-aceti-mide,methylethylamine-4-vinylphenyl-acetimide, trimethylamine-4- 2-propenylphenyl acetimide, trimethylamine-3-(2-propenyl)phenyl-acetimide, andtrimethylamine-Z- 2-propenyl) pheuyl-acetimide.

The novel vinyl aromatic aminimides of the present invention can bepolymerized through addition to the double bond. Although the reactivityof the vinyl group in the aminimide appears to have a reactivity inpolymerization similar to that of the unsubstituted vinyl aromaticmonomer, the presence of the aminimide group in the molecule alters, toa certain degree, the methods employed for polymerization of thesemonomers as compared to the unsubstituted vinyl aromatic monomer. Thus,the aminimide group is sensitive to elevated temperatures above about150 C., as will be explained in greater detail hereinbelow. Hence, it isgenerally desirable to employ polymerization temperatures between roomtemperature and 150 C. and therefore also a free radicalformingpolymerization initiator such as a peroxide. The initiators are of theconventional type and used in conventional concentrations. Additionally,the monomer as well as the homopolymer is generally soluble in polarorganic solvents such as alcohols, esters, ethers and ketones, as wellas mixtures of such polar solvents with water. Hence, contrary to theunsubstituted aromatic vinyl monomers, the aminimides of the presentinvention can be homopolymerized in such polar media. Except for thesedifferences, the polymerization techniques developed for vinyl aromaticmonomers are equally applicable to the monomers of the presentinvention. This is particularly true for the copolymerization of thedescribed aminimides.

The aminimides can be copolymerized in all ratios with unsubstitutedvinyl aromatic monomers such as styrene, wmethyl styrene, oc-ChlOIOstyrene and ring-halogenated styrenes, and such monomers as are capableof copolymerization with styrene such as acrylonitrile, butadiene, andacrylic monomers. The term acrylic monomers is defined as includingmonomers containing the structure Acrylic monomers useful for suchpurpose include ethyl acrylate, methyl acrylate, butyl acrylate, methylmethacrylate, ethyl methacrylate, hydroxy-substituted alkyl acrylatesand methacrylates, alkoxy-substituted alkyl acrylates and methacrylates,acrylic acid, methacrylic acid, glycidyl acrylate, glycidylmethacrylate, and the like. The copolymerization can be conducted inbulk or in a common solvent at temperatures of 25 to C. using aperoxide, an azo-bis-nitrile, or similar free radical initiator. Insteadof polymerizing the aminimide directly, the vinyl aromatic hydraziniumsalt can be polymerized by the methods described and subsequentlyconverted to the polyaminimide by the methods described for theconversion of the monomer.

The utility of the polymers and copolymers of the present invention isbased on their ability to be converted to polyisocyanates which have awell-established utility in the formation of polyurethanes. Theconversion is accomplished by pyrolysis or photolysis. The conversion isillustrated by the following equation in which R R R and n have theabove-indicated meamng.

The tertiary amine by-products are well known catalysts in thepolymerization of isocyanates with hydroxylterminated polyesters,polyethers and polyols.

Pyrolysis of the aminimides can be conducted by heating the aminimide totemperatures above about 150 C., and results in the formation of theisocyanate and a tertiary amine by the above equation.

Although it is possible to convert the vinyl aromatic aminimide of thepresent invention to the isocyanate prior to polymerization, it isgenerally preferred to convert the aminimide subsequent topolymerization in view of the greater chemical stability of theaminimide group as compared to the isocyanate group. This isparticularly significant in the formation of urethane linkages in thesense that the aminimide can be admixed with polyhydroxy compounds andform a stable system. On heating such system, the aminimide is convertedto the isocyanate, which reacts with the polyhydroxy compound, whilesimultaneously releasing a tertiary amine, which acts as a catalyst forthe reaction. It will be apparent, therefore, that the incorporation ofa small number of the novel aminimide monomers into an otherwiseunreactive polymer (i.e., containing no Zerewitinoff hydrogen) convertssuch polymer chains into a crosslinkable system which can be crosslinkedwith a curing agent, i.e., an agent which contains two or moreZerewitinoif hydrogens. The meaning of the term Zerewitinoff hydrogen iswell-established in the polyurethane art and includes, in particular,the hydroxyl group. The polymer systems of the present invention havethe additional advantages of being stable at temperatures below 150 C.in the presence of compounds containing a Zerewitinoff hydrogen.Polymers which contain a higher number of aminimide units have utilityin polyurethane systems which are well-known in the art. The vinylaromatic aminimide canfurthermore be converted to the isocyanate andthen employed directly in polyurethane systems, thereby introducingreactive double bonds into the system. The foregoing discussion of theutility of the vinyl aromatic aminimides of the present invention is notintended to limit the utility of the vinyl aromaic aminimides to such,since many other applications will be apparent to those skilled in theart from the dual reactivity of the vinyl aromatic aminimides.

The formation of the novel aminimides, their polymerization and theirconversion to isocyanates, !38 well as the reactivity of suchisocyanates, is further illustrated by the following examples in whichall units of quantity are by weight unless otherwise stated.

EXAMPLE 1 4-vinyl benzoyl acid chloride was prepared from 5 g. (0.034mole) of 4-vinyl benzoic acid and 6 ml. of thionyl chloride. On solutionin a hydrocarbon solvent, commercially available as Skelly F, filtrationand removal of solvent, 5.4 g. (88%) of purified 4-vinyl benzoyl acidchloride was obtained.

The acid chloride was dissolved in 10 ml. of Skelly F and added dropwiseto a solution of 6 g. of 1,1-dimethylhydrazine in ml. of Skelly Fmaintained at 10 C. After addition (35 minutes), the mixture was stirredat room temperature for 19 additional hours.

The mitxure was filtered and collected solid washed with Skelly F andthen dried. The solid was washed with water to remove the1,1-dimethylhydrazine hydrocholon'de and the solid was dried underreduced pressure. A yield of 4.14 g., M.P. 122125 C. (68%) of 1,1-dimethyl-2-(4-vinylbenzoyl)hydrazine was obtained.

An alternate method for preparing the hydrazine is as follows. To astirred solution of 15 ml. (21 g. 0.35 mole) of 1,1-dimethylhydrazinedissolved in 20 ml. of anhydrous ether is added dropwise a solution of12.4 g. (0.084 mole) of 4-vinylbenzoyl chloride. The mixture is keptbetween 1S-25 C. throughout the addition and after addition is stirredan additional 20 hours at room temperature. The mixture is filtered, andthe white solid Washed with water and dried. The solid (5.12 g., 32%) isrecrystallized from benzene, M.P. -126 C. Infrared and nuclear magneticresonance analysis confirms the structure of the product to be1,1-dimethyl;2-(4-vinylbenzoyl)hydrazine.

In a 300 ml. flask is placed 5 g. of 1,1-dimethyl-2-(4-vinylbenzoyl)hydrazine, 6 g. of methyl tosylate, and 125 ml. ofanhydrous acetonitrile. The solution is heated to reflux and a trace ofhydroquinone added after one-half hour. The reflux is continued for 5additional hours, the solution is cooled to room tempenature thenpermitted to stand for an additional 12 hours at room temperature.

The crystals that form are filtered (5.3 g.) On reducing the volume ofthe mother liquor, an additional 2.9 g. of product is obtained.Recrystallization from methanol-benzene yields white crystals, M.P.166-168 C., total yield 8.1 g. (82% The infrared and nuclear magneticresonance analyses confirm the structure of the product to be 1,1,1trimethyl-2-(4-vinylbenzoyl)hydrazinium tosylate.

Analysis-Calculated for C H N O S (percent): C, 60.61; H, 6.44%; N,7.44. Found (percent): C, 60.78, 60.90; H, 6.53, 6.56; N, 7.43, 7.47.

A solution of 7.2 g. (0.0196 mole) of 1,1,1-trimethyl-2-(4-vinylbenzoyl)hydrazinium tosylate in 35 ml. of anhydrous methanolis titrated to the phenolphthalein end point with 1.108 N. alcoholicNaOH requiring 16.9 ml., 96% theoretical base. The mixture is chilled inan ice bath, sodium tosylate is filtered from the solution and themethanol removed on a rotary evaporator. Chloroform is added to theresidue and the solution is dried over sodium sulfate and filtered.Removal of the chloroform solvent yields a solid which is dissolved inhot benzene. Cyclohexane is added to the hot solution until a gummyyellow material precipitates. After decanting the hot solution, morecyclohexane is added until turbid. Cooling results in white, fluifyneedles, 3.30 g. (79.5% M.P. 122- 124 C. Nuclear magnetic resonance andinfrared analysis confirm the structure of the product to betrimethylamine-4-vinyl-benzimide.

Analysis.Calculated for C H N O (percent): C, 70.57; H, 7.90; N, 13.72.Found (percent): C, 70.68; 70.48; H, 8.02, 7.99; N, 13.44, 13.50.

The aminimide is soluble in water, methanol, ethanol, chloroform, andbenzene, and is insoluble in pentane, cyclohexane, and carbontetrachloride.

EXAMPLE 2 Into a raction flask is charged 100 parts of water, 5 parts ofthe aminimide of Example 1, 0.4 part of ambis-isobutyronitrile,commercially available as VAZO, and enough acetone to solubilize themixture. The solution is heated at reflux for 16 hours, cooled, anddiluted with acetone. The precipitated polymer is collected, washed withacetone, and dried under reduced pressure.

Infrared analysis shows the polymer to substantially have a structure ofrepeating units having the formula 963 ONN(CH3): The polymer is solublein water, methanol, and chloroform.

The polymer is heated to 200225 C. and a quantitative evolution oftrimethylamine is obtained. Analysis of the resulting polymer confirmsthe conversion of the aminimide groups to isocyanate groups.

EXAMPLE 3 Into a reaction flask is charged 100 parts of methyl ethylketone, 2.5 parts of the aminimide of Example 1, 2.5 parts of styrene,and 0.4 part of the catalyst of Example 2. The solution is heated at 60C. for 20 hours. On cooling, a water-soluble copolymer of styrene andtrimethylamine-4-vinyl-benzimide is obtained.

EXAMPLE 4 The procedure of Example 3 is repeated employing 5 parts ofthe aminimide and 3 parts of methyl methacrylate. The resultingwater-soluble copolymer of methyl methacrylate and trimethylamine 4vinyl benzimide evolves trimethylamine on heating to 190 C., saidheating converting the aminimide groups to isocyanate groups.

EXAMPLE 5 The procedure of Example 3 is repeated using 2.5 parts of theaminimide and 2.5 parts of 2-hydroxypropyl methacrylate. The resultingcopolymer is a glass-like solid. A 25% water solution of the polymer isdrawn down on glass and treated for 12 hours at 200 C. The resultingfilm has a thickness of to mils and is hard and scratch-resistant.Infrared analysis of the film shows the loss of the originally presentaminimide groups and the formation of urethane groups. The polymer isinsoluble.

EXAMPLE 6 Into a 100 ml. serum bottle was charged under nitrogen 60 ml.of acetonitrile, 5.2 g. of styrene and 10.2 g. oftrimethylamine-4-vinyl-benzimide corresponding to a 1:1 molar ratio ofthe comonomers. On addition of 0.15 g. of VAZO catalyst, the bottle wassealed and placed in a water bath at 70 C. for a period of four hours.The resulting solid copolymer was isolated by pouring the polymerizationsolution into ether, and was collected by filtration. On drying andremoval of unreacted monomer, the polymer was found to contain about 69mole percent of the benzimide, the remainder being styrene.

EXAMPLE 7 The procedure of Example 6 was repeated employing a monomermixture of mole percent trimethylamine- 4-vinyl-benzimide and 80 molepercent methacrylonitrile. A copolymer containing about 23.4 molepercent of the benzimide and about 76.6 mole percent ofmethacrylonitrile as measured by titration was obtained.

EXAMPLE 8 The procedure of Example 6 was repeated employing a monomermixture of 20 mole percent trimethylamine-4- vinyl-benzimide and 80 molepercent methyl methacrylate. A copolymer containing about 26.4 molepercent of the benzimide and about 73.6 mole percent of methylmethacrylate as measured by titration was obtained.

The foregoing examples have illustrated the preparation andpolymerization of the novel vinyl aromatic aminimides and thepost-polymerization reactions useful in the utilization of polymersprepared from the vinyl aromatic aminimides. It will be apparent thatother vinyl aromatic aminimides included within the scope of the presentinvention can be similarly employed in the specific proceduresillustrated in the examples. Similarly, other methods of polymerizationand other comonomers can be employed, and will be apparent to thoseskilled in the art. Since many variations and embodiments are apparentto those skilled in the art, it is not intended to limit the foregoingdisclosure to the particular features shown.

What is claimed is:

1. The addition polymer of the vinyl aromatic aminimide having theformula wherein R is a hydrogen, halogen, or methyl; n is 0 or 1; R andR are aliphatic hydrocarbon radicals, aryl hydrocarbon radicals, orradicals in which R; and R are combined to form heterocyclic rings withthe nitrogen, and wherein R is an aliphatic hydrocarbon radical of 1 to22 carbon atoms.

2. The addition polymer of claim 1 wherein R R and R are lower alkylradicals or phenyl.

3. The addition polymer of claim 2 wherein the vinyl aromatic aminimideis the sole monomer.

4. The polymer of claim 2 wherein the vinyl aromatic monomer iscopolymerized with styrene or an ethylenically unsaturated monomercapable of copolymerizing with styrene.

5. The polymer of claim 4 wherein the comonomer is styrene,acrylonitrile, butadiene, or an acrylic monomer.

6. The polymer of claim 2 wherein the vinyl aromatic aminimide has theformula wherein R R and R are lower alkyl groups.

7. The polymer of claim 6 wherein the aminimide group is in the'paraposition.

8. The addition polymer of claim 6 wherein R R and R are methyl.

9. The addition polymer of claim 1 wherein R R and R each represent a CC alkyl radical, a phenyl radical, or a substituted phenyl group, andwherein R and R when taken collectively with the nitrogen atom to whichthey are attached, represent a heterocyclic ring selected from a groupconsisting of pyrrolidine, pyrrole, pyrroline, and piperidine.

References Cited UNITED STATES PATENTS 2,468,713 4/1949 Kropa et al 260-NC 2,500,025 3/1950 Dickey et al. 26077.5 BB 3,242,138 3/1966 VanPaesschen 26089.7 N 3,450,673 6/1969 McKillip 251--182 DONALD E. CZAIA,Primary Examiner M. J. WELSH, Assistant Examiner US. Cl. X.R.

260-77.5 TB, 77.5 BB, 80 NC, 85.5 AM, 86.1 N, 88.1 PN, 88.3, 89.7 R,89.7 S, 89.7 N, 93.5 R

